A CNV-distraction paradigm in combat veterans with posttraumatic stress disorder.

Fourteen veterans with posttraumatic stress disorder (PTSD) and 14 without PTSD participated in a contingent negative variation (CNV)-distraction paradigm. Subjects were instructed to press a button after hearing a high-pitched tone (S2) preceded by a low-pitched tone (S1). One-half of the trials included a white-noise distracter placed in the S1-S2 interval. Posttraumatic stress disorder subjects had larger frontal, but smaller central and parietal CNVs, regardless of condition (distracter, no distracter) or epoch (early CNV, late CNV). In PTSD subjects, the N1/P2 complex was smaller to warning (S1) and distracter stimuli and did not show the extent of facilitation present in non-PTSD subjects. Findings highlight PTSD-related differences in phasic cortical excitability and attention.